US20210273830A1 - Communication device and communication method - Google Patents
Communication device and communication method Download PDFInfo
- Publication number
- US20210273830A1 US20210273830A1 US17/184,606 US202117184606A US2021273830A1 US 20210273830 A1 US20210273830 A1 US 20210273830A1 US 202117184606 A US202117184606 A US 202117184606A US 2021273830 A1 US2021273830 A1 US 2021273830A1
- Authority
- US
- United States
- Prior art keywords
- signal
- equalization
- partial response
- zero
- weighted value
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03159—Arrangements for removing intersymbol interference operating in the frequency domain
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
- H04L25/03114—Arrangements for removing intersymbol interference operating in the time domain non-adaptive, i.e. not adjustable, manually adjustable, or adjustable only during the reception of special signals
- H04L25/03146—Arrangements for removing intersymbol interference operating in the time domain non-adaptive, i.e. not adjustable, manually adjustable, or adjustable only during the reception of special signals with a recursive structure
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03178—Arrangements involving sequence estimation techniques
- H04L25/03248—Arrangements for operating in conjunction with other apparatus
- H04L25/03254—Operation with other circuitry for removing intersymbol interference
- H04L25/03267—Operation with other circuitry for removing intersymbol interference with decision feedback equalisers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/38—Synchronous or start-stop systems, e.g. for Baudot code
- H04L25/40—Transmitting circuits; Receiving circuits
- H04L25/49—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems
- H04L25/4917—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems using multilevel codes
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L2025/03592—Adaptation methods
- H04L2025/03598—Algorithms
- H04L2025/03611—Iterative algorithms
- H04L2025/03617—Time recursive algorithms
- H04L2025/03624—Zero-forcing
Definitions
- the present invention relates to a communication device that decodes a signal received in a communication network and a communication method used in the communication device.
- Partial Response Maximum Likelihood is used as a method of decoding a signal read from a recording medium such as an optical disc or a magnetic disc.
- JP 2011-227970 A and JP 2006-121285 A a signal is decoded by execution of two types of partial response equalization in a recording-reproducing device.
- An object of the present invention is to further lower a symbol error rate in a decoding method utilizing partial response equalization.
- a communication device includes circuitry configured to receive a receipt signal and execute zero-forcing equalization on the receipt signal, receive the receipt signal and execute partial response equalization on the receipt signal, calculate a first weighted value based on signal quality of the receipt signal on which the zero-forcing equalization has been executed, calculate a second weighted value based on signal quality of the receipt signal on which the partial response equalization has been executed, and estimate a maximum likelihood sequence by supplying the first weighted value to state transition based on output from the zero-forcing equalization and supplying the second weighted value to state transition based on output from the partial response equalization.
- the zero-forcing equalization may include a procedure to be processed by a zero-forcing equalization slicer
- the partial response equalization may include a procedure to be processed by a partial response equalization slicer
- the calculating a first weighted value may include calculating the first weighted value based on a signal-to-noise ratio of the zero-forcing equalization slicer
- the calculating a second weighted value may include calculating the second weighted value based on a signal-to-noise ratio of the partial response equalization slicer.
- the first weighted value may have a positive correlation with the signal-to-noise ratio of the zero-forcing equalization slicer, and may have a negative correlation with a sum of the signal-to-noise ratio of the zero-forcing equalization slicer and the signal-to-noise ratio of the partial response equalization slicer
- the second weighted value may have a positive correlation with the signal-to-noise ratio of the partial response equalization slicer, and may have a negative correlation with a sum of the signal-to-noise ratio of the zero-forcing equalization slicer and the signal-to-noise ratio of the partial response equalization slicer.
- the receipt signal may be a signal on which PAM4 mapping has been executed, and the partial response equalization slicer may output the receipt signal as a symbol having seven levels.
- the zero-forcing equalization may include a procedure to be processed by a Decision Feedback Equalizer.
- the partial response equalization may include a procedure to be processed by a Decision Feedback Equalizer.
- a communication method includes executing zero-forcing equalization on a receipt signal, executing partial response equalization on the receipt signal, calculating a first weighted value based on signal quality of the receipt signal on which the zero-forcing equalization has been executed, calculating a second weighted value based on signal quality of the receipt signal on which the partial response equalization has been executed, and estimating a maximum likelihood sequence by supplying the first weighted value to state transition based on output from the zero-forcing equalization and supplying the second weighted value to state transition based on output from the partial response equalization.
- FIG. 1 is a diagram showing a communication system including a communication device according to embodiments
- FIG. 2 is a schematic diagram showing the communication device according to the embodiments.
- FIG. 3 is a block diagram showing the configurations of a transmitter and a receiver included in the communication device
- FIG. 4 is a diagram showing frequency property of a signal received via a channel
- FIG. 5 is a diagram showing property of an equalizer
- FIG. 6 is a circuit diagram showing a Feed Forward Equalizer (FFE);
- FIG. 7 is a circuit diagram showing a Decision Feedback Equalizer (DFE).
- DFE Decision Feedback Equalizer
- FIG. 8 is a diagram showing a signal sequence of partial response of a class PR 1 ;
- FIG. 9 is a trellis diagram to which a maximum likelihood sequence estimator refers.
- FIG. 10 is a diagram showing a result of experiment in which receiving property is compared between the communication device according to the embodiment and a conventional communication device.
- FIG. 1 is a diagram showing a communication system 10 including the communication devices 1 according to the embodiments.
- the communication system 10 includes the plurality of communication devices 1 and Ethernet 2 .
- the plurality of communication devices 1 are connected to be communicable with one another via the Ethernet 2 .
- the Ethernet 2 is a communication standard defined as IEEE 802.3 and constitutes a LAN (Local Area Network). For example, 2.5G BASE-T, SG BASE-T or 10G BASE-T is used for the Ethernet 2 .
- a twisted pair cable compatible with the category 5e/6 is used in case of 2.5G BASE-T/5G BASE-T, and a twisted pair cable compatible with the category 6 A is used in case of 10G BASE-T.
- the communication system 10 including the communication devices 1 and the Ethernet 2 is installed in various establishments such as offices, commercial buildings and stations. Alternatively, the communication system 10 is used for personal use and used in houses, apartments, etc. Alternatively, the communication system 10 may be used in vehicles such as trains or automobiles.
- FIG. 2 is a schematic diagram showing the configuration of the communication device 1 .
- the communication device 1 includes a transmitter 3 and a receiver 4 .
- the transmitter 3 encodes a signal and transmits the encoded signal to a communication device 1 which is a counter device.
- the signal transmitted from the transmitter 3 is transmitted to the communication device 1 which is the counter device via the Ethernet 2 .
- the receiver 4 receives a signal transmitted from a communication device 1 which is a counter device via the Ethernet 2 .
- FIG. 3 is a block diagram showing the configuration of the transmitter 3 and the receiver 4 included in the communication device 1 .
- a receiver 4 included in one communication device 1 receives a signal transmitted by a transmitter 3 in another communication device 1 via a channel 20 .
- the channel 20 is a transmission line between the transmitter 3 and the receiver 4 .
- the transmission line that goes through the Ethernet 2 is the channel 20 .
- the transmitter 3 includes a Pulse Amplitude Modulation 4-level mapper 31 (hereinafter abbreviated as a PAM4 mapper 31 ).
- the PAM4 mapper 31 maps a transmission signal into four levels—“00,” “01,” “10,” and “11.” Then, the transmitter 3 transmits the signal, which is mapped by the PAM4 mapper 31 and has four levels, using four voltage levels.
- the transmitter 3 modulates a signal having four levels into four signal levels of ⁇ 1, ⁇ 1/3, 1/3, 1 ⁇ , by way of example.
- the transmitter 3 encodes and modulates the signal in accordance with an encoding scheme defined by IEEE 802.3ch, for example.
- the receiver 4 includes a zero-forcing equalizer 4 A and a partial response equalizer 4 B.
- the zero-forcing equalizer 4 A executes a normal equalization process which is referred to as Zero-Forcing (ZF) for removing intersymbol interference in a received sequence.
- the zero-forcing equalizer 4 A includes a Feed Forward Equalizer (hereinafter abbreviated as an FFE) 41 A, an adder 42 A, a zero-forcing equalization slicer 43 A and a Decision Feedback Equalizer (hereinafter abbreviated as a DFE) 44 A.
- FFE Feed Forward Equalizer
- DFE Decision Feedback Equalizer
- the partial response equalizer 4 B executes an equalization process such that the output has specific partial response property.
- the partial response equalizer 4 B includes an FFE 41 B, an adder 42 B, a partial response equalization slicer 43 B and a DFE 44 B.
- the receiver 4 further includes a weighted value calculator 45 A, a weighted value calculator 45 B and a Maximum Likelihood Sequence Estimator (MLSE) 46 .
- the weighted value calculator 45 A is an example of a calculator calculating a first weighted value in the present invention.
- the weighted value calculator 45 B is an example of a calculator calculating a second weighted value in the present invention.
- the Maximum Likelihood Sequence Estimator 46 is an example of an estimator in the present invention.
- FIGS. 4 and 5 are diagrams for explaining the zero-forcing equalization process and the partial response equalization process.
- FIG. 4 is a diagram showing the frequency property of a signal received via a channel.
- the ordinate indicates a loss (dB) of a receipt signal
- the abscissa indicates frequency (MHz) of a receipt signal.
- the graph C 1 indicates the frequency property of a receipt signal that has suffered insertion loss in the channel
- the graph C 2 indicates the frequency property of a receipt signal that has passed through a partial response channel.
- FIG. 5 is a diagram showing the property of equalizers.
- the ordinate indicates an amplification value (dB) of a signal
- the abscissa indicates frequency (MHz) of an amplifying signal.
- the graph E 1 indicates the equalizer property for zero-forcing equalization of a receipt signal that has suffered insertion loss
- the graph E 2 indicates equalizer property for partial response equalization of a receipt signal that has suffered insertion loss.
- the graph C 1 of FIG. 4 indicates the frequency property of a receipt signal in a case where the signal suffers insertion loss via the channel.
- an equalization process having the property of the graph E 1 of FIG. 5 is executed on a receipt signal having the property of the graph C 1 .
- the receipt signal is amplified such that the loss is close to 0 (dB) in all frequency bands.
- an equalization process having the property of the graph E 2 of FIG. 5 is executed on a receipt signal having the property of the graph C 1 .
- the receipt signal has the property similar to the property shown by the graph C 2 of FIG. 4 . That is, due to the partial response equalization process, the receipt signal that has suffered the insertion loss has the property of a receipt signal that has passed through the partial response channel.
- the FFE 41 A and the FFE 41 B receive a signal that has passed through the channel 20 .
- An Additive White Gaussian Noise (AWGN) is added to the receipt signal.
- the FFE 41 A and the FFE 41 B compensate ISI (Intersymbol Interference) jitter of the channel 20 by using an FIR (Finite Impulse Response) filter.
- FIR Finite Impulse Response
- FIG. 6 shows one example of the circuit configuration of an FIR filter used as each of the FFE 41 A and the FFE 41 B.
- Each of the FFE 41 A and the FFE 41 B shown in FIG. 6 is an FIR filter with three taps and includes delayers 61 , 62 , multipliers 63 , 64 , 65 and an adder 66 .
- a present signal is multiplied by a predetermined filter coefficient by the multiplier 63
- delay signals are multiplied by a predetermined filter coefficient by the multipliers 64 , 65 .
- the present signal and the delay signals multiplied by the filter coefficients are added to each other by the adder 66 .
- the adder 42 A adds an output signal of the FFE 41 A and an output signal of the DFE 44 A to each other.
- the signal added by the adder 42 A is input to the zero-forcing equalization slicer 43 A.
- the adder 42 B adds an output signal of the FFE 41 B and an output signal of the DFE 44 B to each other.
- the signal added in the adder 42 B is input to the partial response equalization slicer 43 B.
- the zero-forcing equalization slicer 43 A receives the sum signal of the output of the FFE 41 A and the output of the DFE 44 A.
- the zero-forcing equalization slicer 43 A is a four-level slicer and outputs the signal value of a receipt signal as a symbol having four levels by comparing the signal value of the receipt signal with a threshold value.
- the zero-forcing equalization slicer 43 A outputs the signal value of the receipt signal as a symbol having the four levels of ⁇ 1, ⁇ 1/3, 1/3, 1 ⁇ .
- the partial response equalization slicer 43 B receives the sum signal of the output of the FFE 41 B and the output of the DFE 44 B.
- the partial response equalization slicer 43 B is a seven-level slicer and outputs the signal value of a receipt signal as a symbol having seven levels by comparing the signal value of the receipt signal with a threshold value.
- the partial response equalization slicer 43 B outputs the signal value of a receipt signal as a symbol having the seven levels of ⁇ 2, ⁇ 4/3, ⁇ 2/3, 0, 2/3, 4/3, 2 ⁇ .
- FIG. 8 is a diagram showing a signal sequence in partial response of a class PR 1 . That is, FIG. 8 is a diagram showing the signal sequence in a transmission line in which (1+D) deterioration of frequency property occurs.
- the transmitter 3 modulates a signal into four signal levels of ⁇ 1, ⁇ 1/3, 1/3, 1 ⁇ for transmission. Therefore, either of the signal sequences ⁇ Sn ⁇ 1 ⁇ , ⁇ Sn ⁇ transmitted by the transmitter 3 has four signal levels of ⁇ 1, ⁇ 1/3, 1/3, 1 ⁇ .
- the partial response ⁇ Pn ⁇ of this signal sequence in the class PR 1 has property of (1+D), thereby being a signal having seven levels of ⁇ 2, ⁇ 4/3, ⁇ 2/3, 0, 2/3, 4/3, 2 ⁇ . That is, property of the receipt signal that has suffered insertion loss is equalized to property of partial response by outputting a receipt signal as a symbol having seven levels by the partial response equalization slicer 43 B.
- the DFE 44 A receives the output from the zero-forcing equalization slicer 43 A and compensates ISI jitter of the channel 20 .
- the DFE 44 B receives the output from the partial response equalization slicer 43 B and compensates ISI jitter of the channel 20 .
- Each of the DFEs 44 A, 44 B is a circuit that includes a delayer with multiple taps (two taps, three taps or the like) and multiplies each delay signal by a coefficient.
- FIG. 7 One example of the circuit configuration of each of the DFE 44 A and the DFE 44 B is shown in FIG. 7 .
- each of the DFE 44 A and the DFE 44 B is a DFE with two taps and includes delayers 71 , 72 , multipliers 73 , 74 and an adder 75 as shown in FIG. 7 .
- a delay signal is multiplied by a predetermined filter coefficient by each of the multipliers 73 , 74 .
- the delay signals multiplied by the filter coefficient are added by the adder 75 .
- the weighted value calculator 45 A calculates a weighted value with respect to a signal output from the zero-forcing equalizer 4 A.
- the weighted value calculator 45 B calculates a weighted value with respect to a signal output from the partial response equalizer 4 B.
- An example of calculation of a weighted value by the weighted value calculators 45 A, 45 B will be shown below.
- the signal-to-noise ratios SNRs, SNRp are expressed by the formula 3 and the formula 4.
- the signal-to-noise ratio SNRs is the ratio of a value obtained by integration of the square of the signal Sn in the time direction with respect to a value obtained by integration of the square of the noise Se in the time direction.
- the signal-to-noise ratio SNRp is the ratio of a value obtained by integration of the square of the signal Pn in the time direction with respect to a value obtained by integration of the square of the noise Pe in the time direction.
- the signal-to-noise ratio SNRs is an example of signal quality of the receipt signal calculated by the zero-forcing equalizer in the present invention
- the signal-to-noise ratio SNRp is an example of signal quality of the receipt signal calculated by the partial response equalizer in the present invention.
- a weighted value with respect to an output signal of the zero-forcing equalization slicer 43 A be W(Sn)
- W(Sn) and W(Pn) are expressed by the formula 5 and the formula 6.
- the weighted value W(Sn) has a positive correlation with the signal-to-noise ratio SNRs of the zero-forcing equalization slicer 43 A, and has a negative correlation with the sum of the signal-to-noise ratio SNRs of the zero-forcing equalization slicer 43 A and the signal-to-noise ratio SNRp of the partial response equalization slicer 43 B.
- the weighted value W(Pn) has a positive correlation with the signal-to-noise ratio SNRp of the partial response equalization slicer 43 B, and has a negative correlation with the sum of the signal-to-noise ratio SNRs of the zero-forcing equalization slicer 43 A and the signal-to-noise ratio SNRp of the partial response equalization slicer 43 B.
- the weighted value calculators 45 A, 45 B calculate the weighted values W(Sn), W(Pn), respectively and supplies the calculated weighted values W(Sn), W(Pn) to the maximum likelihood sequence estimator 46 .
- the maximum likelihood sequence estimator 46 estimates a maximum likelihood sequence based on the weighted values W(Sn), W(Pn) supplied from the weighted value calculators 45 A, 45 B.
- FIG. 9 is a trellis diagram to which the maximum likelihood sequence estimator 46 refers.
- a signal Sn transmitted by the transmitter 3 is a signal on which PAM4 mapping has been executed and has four levels of ⁇ 1, ⁇ 1/3, 1/3, 1 ⁇ .
- a signal Pn on which partial response equalization has been executed is a signal having seven levels of ⁇ 2, ⁇ 4/3, ⁇ 2/3, 0, 2/3, 4/3, 2 ⁇ .
- the maximum likelihood sequence estimator 46 calculates a weighted likelihood Lw(Pn) in regard to each transition in the trellis diagram with use of the weighted values W(Sn), W(Pn). Further, the maximum likelihood sequence estimator 46 estimates the transition that has the largest weighted likelihood LW(Pn) as a maximum likelihood sequence.
- the communication device 1 of the present embodiment includes a weighted value calculator 45 A that calculates a weighted value W(Sn) based on the signal quality of a receipt signal output from the zero-forcing equalizer 4 A and a weighted value calculator 45 B that calculates a weighted value W(Pn) based on the signal quality of a receipt signal output from the partial response equalizer 4 B.
- the maximum likelihood sequence estimator 46 of the communication device 1 supplies a weighted value W(Sn) to the state transition based on the output of the zero-forcing equalizer 4 A and supplies a weighted value W(Pn) to the state transition based on the output of the partial response equalizer 4 B, thereby estimating a maximum likelihood sequence.
- the communication device 1 of the present embodiment can weight the signal obtained by zero-forcing equalization and partial response equalization in accordance with property of a transmission line for utilization. Thus, a symbol error rate in the communication device 1 can be lowered.
- FIG. 10 is a diagram showing a result of experiment in which receiving property is compared between the communication device 1 according to the embodiment and a conventional communication device.
- the graph G 1 represents the relationship between the signal-to-noise ratio of a receipt signal and the symbol error rate in a case where a conventional zero-forcing equalization process is utilized.
- the graph G 2 represents the relationship between the signal-to-noise ratio of a receipt signal and the symbol error rate in a case where a conventional partial response equalization process is utilized.
- the graph G 3 represents the relationship between the signal-to-noise ratio of a receipt signal and the symbol error rate in a case where the communication device 1 in the present embodiment is utilized, that is, in a case where the hybrid configuration of the zero-forcing equalization process and the partial response equalization process is utilized. All of the graphs G 1 to G 3 represent data acquired in the environment of 10G BASE-T. As shown in FIG.
- the communication device 1 of the present embodiment can realize a similar symbol error rate even in a case where a signal-to-noise ratio is lower than a signal-to-noise ratio acquired in a zero-forcing equalization process by about 2 to 3 db and is lower than a signal-to-noise ratio acquired in a partial response equalization process by about 1 to 2 dB.
- the partial response equalizer 4 B executes partial response equalization of the class PR 1 , by way of example.
- a partial response equalizer 4 B may be configured to execute partial response equalization corresponding to other classes (PR 2 to PR 5 , etc.)
- the zero-forcing equalizer 4 A is configured to include the DFE 44 A
- the partial response equalizer 4 B is configured to include the DFE 44 B.
- a zero-forcing equalizer 4 A may be configured not to include a DFE
- a partial response equalizer 4 B may be configured not to include a DFE.
- the weighted value calculators 45 A, 45 B calculate the weighted values W(Sn), W(Pn) each time based on a signal-to-noise ratio SNRs of the signal Sn received by the zero-forcing equalization slicer 43 A and a signal-to-noise ratio SNRp of the signal Pn received by the partial response equalization slicer 43 B.
- several expected values may be stored in a table in advance, and an appropriate expected value may be set as a weighted value in accordance with the state of a transmission line.
- the PAM4 mapping is executed on a transmission signal by way of example.
- the communication device 1 of the present embodiment can be applied to other modulation systems such as PAM2, PAM3, PAM5, PAM8, PAM16 and NRZ.
- circuitry or processing circuitry which includes general purpose processors, special purpose processors, integrated circuits, ASICs (“Application Specific Integrated Circuits”), conventional circuitry and/or combinations thereof which are configured or programmed to perform the disclosed functionality.
- Processors are considered processing circuitry or circuitry as they include transistors and other circuitry therein.
- the circuitry, units, or means are hardware that carry out or are programmed to perform the recited functionality.
- the hardware may be any hardware disclosed herein or otherwise known which is programmed or configured to carry out the recited functionality.
- the hardware is a processor which may be considered a type of circuitry
- the circuitry, means, or units are a combination of hardware and software, the software being used to configure the hardware and/or processor.”
Abstract
Description
- This application claims priority to Japanese Patent Application No. 2020-031553 filed on Feb. 27, 2020, the content of which is incorporated herein by reference.
- The present invention relates to a communication device that decodes a signal received in a communication network and a communication method used in the communication device.
- Partial Response Maximum Likelihood (PRML) is used as a method of decoding a signal read from a recording medium such as an optical disc or a magnetic disc.
- In the Partial Response Maximum Likelihood, it is possible to suppress noise amplification caused during equalization by executing partial response equalization that allows specific intersymbol interference.
- In JP 2011-227970 A and JP 2006-121285 A, a signal is decoded by execution of two types of partial response equalization in a recording-reproducing device.
- It is possible to suppress noise amplification caused by equalization and lower a symbol error rate by using the Partial Response Maximum Likelihood. However, noise amplifying property of a channel varies. Even in a case where the partial response equalization is utilized, there is a further demand to lower a symbol error rate. In the field of high-speed communication technique in particular, there is a great demand to lower a symbol error rate.
- An object of the present invention is to further lower a symbol error rate in a decoding method utilizing partial response equalization.
- A communication device according to one aspect of the present invention includes circuitry configured to receive a receipt signal and execute zero-forcing equalization on the receipt signal, receive the receipt signal and execute partial response equalization on the receipt signal, calculate a first weighted value based on signal quality of the receipt signal on which the zero-forcing equalization has been executed, calculate a second weighted value based on signal quality of the receipt signal on which the partial response equalization has been executed, and estimate a maximum likelihood sequence by supplying the first weighted value to state transition based on output from the zero-forcing equalization and supplying the second weighted value to state transition based on output from the partial response equalization.
- The zero-forcing equalization may include a procedure to be processed by a zero-forcing equalization slicer, the partial response equalization may include a procedure to be processed by a partial response equalization slicer, and the calculating a first weighted value may include calculating the first weighted value based on a signal-to-noise ratio of the zero-forcing equalization slicer, and the calculating a second weighted value may include calculating the second weighted value based on a signal-to-noise ratio of the partial response equalization slicer.
- The first weighted value may have a positive correlation with the signal-to-noise ratio of the zero-forcing equalization slicer, and may have a negative correlation with a sum of the signal-to-noise ratio of the zero-forcing equalization slicer and the signal-to-noise ratio of the partial response equalization slicer, and the second weighted value may have a positive correlation with the signal-to-noise ratio of the partial response equalization slicer, and may have a negative correlation with a sum of the signal-to-noise ratio of the zero-forcing equalization slicer and the signal-to-noise ratio of the partial response equalization slicer.
- The receipt signal may be a signal on which PAM4 mapping has been executed, and the partial response equalization slicer may output the receipt signal as a symbol having seven levels.
- The zero-forcing equalization may include a procedure to be processed by a Decision Feedback Equalizer.
- The partial response equalization may include a procedure to be processed by a Decision Feedback Equalizer.
- A communication method according to yet another aspect of the present invention includes executing zero-forcing equalization on a receipt signal, executing partial response equalization on the receipt signal, calculating a first weighted value based on signal quality of the receipt signal on which the zero-forcing equalization has been executed, calculating a second weighted value based on signal quality of the receipt signal on which the partial response equalization has been executed, and estimating a maximum likelihood sequence by supplying the first weighted value to state transition based on output from the zero-forcing equalization and supplying the second weighted value to state transition based on output from the partial response equalization.
- Other features, elements, characteristics, and advantages of the present disclosure will become more apparent from the following description of preferred embodiments of the present disclosure with reference to the attached drawings.
-
FIG. 1 is a diagram showing a communication system including a communication device according to embodiments; -
FIG. 2 is a schematic diagram showing the communication device according to the embodiments; -
FIG. 3 is a block diagram showing the configurations of a transmitter and a receiver included in the communication device; -
FIG. 4 is a diagram showing frequency property of a signal received via a channel; -
FIG. 5 is a diagram showing property of an equalizer; -
FIG. 6 is a circuit diagram showing a Feed Forward Equalizer (FFE); -
FIG. 7 is a circuit diagram showing a Decision Feedback Equalizer (DFE); -
FIG. 8 is a diagram showing a signal sequence of partial response of a class PR1; -
FIG. 9 is a trellis diagram to which a maximum likelihood sequence estimator refers; and -
FIG. 10 is a diagram showing a result of experiment in which receiving property is compared between the communication device according to the embodiment and a conventional communication device. - A communication device and a communication method according to embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a diagram showing acommunication system 10 including thecommunication devices 1 according to the embodiments. Thecommunication system 10 includes the plurality ofcommunication devices 1 and Ethernet 2. The plurality ofcommunication devices 1 are connected to be communicable with one another via the Ethernet 2. The Ethernet 2 is a communication standard defined as IEEE 802.3 and constitutes a LAN (Local Area Network). For example, 2.5G BASE-T, SG BASE-T or 10G BASE-T is used for the Ethernet 2. In regard to a physical layer of the Ethernet 2, a twisted pair cable compatible with the category 5e/6 is used in case of 2.5G BASE-T/5G BASE-T, and a twisted pair cable compatible with the category 6A is used in case of 10G BASE-T. - The
communication system 10 including thecommunication devices 1 and the Ethernet 2 is installed in various establishments such as offices, commercial buildings and stations. Alternatively, thecommunication system 10 is used for personal use and used in houses, apartments, etc. Alternatively, thecommunication system 10 may be used in vehicles such as trains or automobiles. -
FIG. 2 is a schematic diagram showing the configuration of thecommunication device 1. Thecommunication device 1 includes atransmitter 3 and areceiver 4. Thetransmitter 3 encodes a signal and transmits the encoded signal to acommunication device 1 which is a counter device. The signal transmitted from thetransmitter 3 is transmitted to thecommunication device 1 which is the counter device via the Ethernet 2. Thereceiver 4 receives a signal transmitted from acommunication device 1 which is a counter device via the Ethernet 2. -
FIG. 3 is a block diagram showing the configuration of thetransmitter 3 and thereceiver 4 included in thecommunication device 1. As shown inFIG. 3 , areceiver 4 included in onecommunication device 1 receives a signal transmitted by atransmitter 3 in anothercommunication device 1 via achannel 20. Thechannel 20 is a transmission line between thetransmitter 3 and thereceiver 4. In the present embodiment, the transmission line that goes through the Ethernet 2 is thechannel 20. - As shown in
FIG. 3 , thetransmitter 3 includes a Pulse Amplitude Modulation 4-level mapper 31 (hereinafter abbreviated as a PAM4 mapper 31). The PAM4 mapper 31 maps a transmission signal into four levels—“00,” “01,” “10,” and “11.” Then, thetransmitter 3 transmits the signal, which is mapped by thePAM4 mapper 31 and has four levels, using four voltage levels. Here, thetransmitter 3 modulates a signal having four levels into four signal levels of {−1, −1/3, 1/3, 1}, by way of example. Thetransmitter 3 encodes and modulates the signal in accordance with an encoding scheme defined by IEEE 802.3ch, for example. - As shown in
FIG. 3 , thereceiver 4 includes a zero-forcing equalizer 4A and apartial response equalizer 4B. The zero-forcingequalizer 4A executes a normal equalization process which is referred to as Zero-Forcing (ZF) for removing intersymbol interference in a received sequence. The zero-forcing equalizer 4A includes a Feed Forward Equalizer (hereinafter abbreviated as an FFE) 41A, anadder 42A, a zero-forcing equalization slicer 43A and a Decision Feedback Equalizer (hereinafter abbreviated as a DFE) 44A. - On the assumption that specific intersymbol interference is present, the
partial response equalizer 4B executes an equalization process such that the output has specific partial response property. Thepartial response equalizer 4B includes anFFE 41B, anadder 42B, a partial response equalization slicer 43B and a DFE 44B. - The
receiver 4 further includes aweighted value calculator 45A, aweighted value calculator 45B and a Maximum Likelihood Sequence Estimator (MLSE) 46. Theweighted value calculator 45A is an example of a calculator calculating a first weighted value in the present invention. Further, theweighted value calculator 45B is an example of a calculator calculating a second weighted value in the present invention. Further, the MaximumLikelihood Sequence Estimator 46 is an example of an estimator in the present invention. - Next, a zero-forcing equalization process and a partial response equalization process to be executed by the
receiver 4 in the present embodiment will be described.FIGS. 4 and 5 are diagrams for explaining the zero-forcing equalization process and the partial response equalization process.FIG. 4 is a diagram showing the frequency property of a signal received via a channel. InFIG. 4 , the ordinate indicates a loss (dB) of a receipt signal, and the abscissa indicates frequency (MHz) of a receipt signal. InFIG. 4 , the graph C1 indicates the frequency property of a receipt signal that has suffered insertion loss in the channel, and the graph C2 indicates the frequency property of a receipt signal that has passed through a partial response channel. -
FIG. 5 is a diagram showing the property of equalizers. InFIG. 5 , the ordinate indicates an amplification value (dB) of a signal, and the abscissa indicates frequency (MHz) of an amplifying signal. InFIG. 5 , the graph E1 indicates the equalizer property for zero-forcing equalization of a receipt signal that has suffered insertion loss, and the graph E2 indicates equalizer property for partial response equalization of a receipt signal that has suffered insertion loss. - The graph C1 of
FIG. 4 indicates the frequency property of a receipt signal in a case where the signal suffers insertion loss via the channel. In the zero-forcing equalization process, an equalization process having the property of the graph E1 ofFIG. 5 is executed on a receipt signal having the property of the graph C1. After the zero-forcing equalization process, the receipt signal is amplified such that the loss is close to 0 (dB) in all frequency bands. - In contrast, in the partial response equalization process, an equalization process having the property of the graph E2 of
FIG. 5 is executed on a receipt signal having the property of the graph C1. After the partial response equalization process, the receipt signal has the property similar to the property shown by the graph C2 ofFIG. 4 . That is, due to the partial response equalization process, the receipt signal that has suffered the insertion loss has the property of a receipt signal that has passed through the partial response channel. - Next, the specific configuration of the
receiver 4 will be described while reference is made toFIG. 3 again. TheFFE 41A and theFFE 41B receive a signal that has passed through thechannel 20. An Additive White Gaussian Noise (AWGN) is added to the receipt signal. TheFFE 41A and theFFE 41B compensate ISI (Intersymbol Interference) jitter of thechannel 20 by using an FIR (Finite Impulse Response) filter. For example, an FIR filter with two taps, three taps or the like can be used as each of theFFE 41A and theFFE 41B.FIG. 6 shows one example of the circuit configuration of an FIR filter used as each of theFFE 41A and theFFE 41B. Each of theFFE 41A and theFFE 41B shown inFIG. 6 is an FIR filter with three taps and includesdelayers multipliers adder 66. A present signal is multiplied by a predetermined filter coefficient by themultiplier 63, and delay signals are multiplied by a predetermined filter coefficient by themultipliers adder 66. - The
adder 42A adds an output signal of theFFE 41A and an output signal of theDFE 44A to each other. The signal added by theadder 42A is input to the zero-forcingequalization slicer 43A. Theadder 42B adds an output signal of theFFE 41B and an output signal of theDFE 44B to each other. The signal added in theadder 42B is input to the partialresponse equalization slicer 43B. - The zero-forcing
equalization slicer 43A receives the sum signal of the output of theFFE 41A and the output of theDFE 44A. The zero-forcingequalization slicer 43A is a four-level slicer and outputs the signal value of a receipt signal as a symbol having four levels by comparing the signal value of the receipt signal with a threshold value. As described above, in a case where a signal transmitted by thetransmitter 3 is modulated into four signal levels of {−1, −1/3, 1/3, 1}, for example, the zero-forcingequalization slicer 43A outputs the signal value of the receipt signal as a symbol having the four levels of {−1, −1/3, 1/3, 1}. - The partial
response equalization slicer 43B receives the sum signal of the output of theFFE 41B and the output of theDFE 44B. The partialresponse equalization slicer 43B is a seven-level slicer and outputs the signal value of a receipt signal as a symbol having seven levels by comparing the signal value of the receipt signal with a threshold value. As described above, in a case where a signal transmitted by thetransmitter 3 is modulated into four signal levels of {−1, −1/3, 1/3, 1}, for example, the partialresponse equalization slicer 43B outputs the signal value of a receipt signal as a symbol having the seven levels of {−2, −4/3, −2/3, 0, 2/3, 4/3, 2}. - The meaning of output of the signal value of a receipt signal as a symbol having the seven levels of {−2, −4/3, −2/3, 0, 2/3, 4/3, 2} by the partial
response equalization slicer 43B will be described below.FIG. 8 is a diagram showing a signal sequence in partial response of a class PR1. That is,FIG. 8 is a diagram showing the signal sequence in a transmission line in which (1+D) deterioration of frequency property occurs. Thetransmitter 3 modulates a signal into four signal levels of {−1, −1/3, 1/3, 1} for transmission. Therefore, either of the signal sequences {Sn−1}, {Sn} transmitted by thetransmitter 3 has four signal levels of {−1, −1/3, 1/3, 1}. The partial response {Pn} of this signal sequence in the class PR1 has property of (1+D), thereby being a signal having seven levels of {−2, −4/3, −2/3, 0, 2/3, 4/3, 2}. That is, property of the receipt signal that has suffered insertion loss is equalized to property of partial response by outputting a receipt signal as a symbol having seven levels by the partialresponse equalization slicer 43B. - The
DFE 44A receives the output from the zero-forcingequalization slicer 43A and compensates ISI jitter of thechannel 20. TheDFE 44B receives the output from the partialresponse equalization slicer 43B and compensates ISI jitter of thechannel 20. Each of theDFEs DFE 44A and theDFE 44B is shown inFIG. 7 . In the present embodiment, each of theDFE 44A and theDFE 44B is a DFE with two taps and includesdelayers multipliers adder 75 as shown inFIG. 7 . A delay signal is multiplied by a predetermined filter coefficient by each of themultipliers adder 75. - The
weighted value calculator 45A calculates a weighted value with respect to a signal output from the zero-forcingequalizer 4A. Theweighted value calculator 45B calculates a weighted value with respect to a signal output from thepartial response equalizer 4B. An example of calculation of a weighted value by theweighted value calculators - Letting a signal value received by the zero-forcing
equalization slicer 43A be Sn, and letting a signal value received by the partialresponse equalization slicer 43B be Pn. Letting an output signal determined by the zero-forcingequalization slicer 43A be Q(Sn), and letting an output signal determined by the partialresponse equalization slicer 43B be Q(Pn). In this case, letting a noise of the signal Sn received by the zero-forcingequalization slicer 43A be Se, and letting a noise of the signal Pn received by the partialresponse equalization slicer 43B be Pe, the noises Se, Pe are expressed by theformula 1 and theformula 2. -
[Formula 1] -
S e =Q(S n)−S n (1) -
[Formula 2] -
P e =Q(P n)−P n (2) - Letting a signal-to-noise ratio of the signal Sn received by the zero-forcing
equalization slicer 43A be SNRs, and letting a signal-to-noise ratio of the signal Pn received by the partialresponse equalization slicer 43B be SNRp, the signal-to-noise ratios SNRs, SNRp are expressed by theformula 3 and theformula 4. As expressed by theformula 3 and theformula 4, the signal-to-noise ratio SNRs is the ratio of a value obtained by integration of the square of the signal Sn in the time direction with respect to a value obtained by integration of the square of the noise Se in the time direction. The signal-to-noise ratio SNRp is the ratio of a value obtained by integration of the square of the signal Pn in the time direction with respect to a value obtained by integration of the square of the noise Pe in the time direction. -
- The signal-to-noise ratio SNRs is an example of signal quality of the receipt signal calculated by the zero-forcing equalizer in the present invention, and the signal-to-noise ratio SNRp is an example of signal quality of the receipt signal calculated by the partial response equalizer in the present invention.
- Further, letting a weighted value with respect to an output signal of the zero-forcing
equalization slicer 43A be W(Sn), and letting a weighted value with respect to an output signal of the partialresponse equalization slicer 43B be W(Pn), W(Sn) and W(Pn) are expressed by theformula 5 and theformula 6. -
- As expressed by the
formula 5, the weighted value W(Sn) has a positive correlation with the signal-to-noise ratio SNRs of the zero-forcingequalization slicer 43A, and has a negative correlation with the sum of the signal-to-noise ratio SNRs of the zero-forcingequalization slicer 43A and the signal-to-noise ratio SNRp of the partialresponse equalization slicer 43B. Further, as expressed by theformula 6, the weighted value W(Pn) has a positive correlation with the signal-to-noise ratio SNRp of the partialresponse equalization slicer 43B, and has a negative correlation with the sum of the signal-to-noise ratio SNRs of the zero-forcingequalization slicer 43A and the signal-to-noise ratio SNRp of the partialresponse equalization slicer 43B. - The
weighted value calculators likelihood sequence estimator 46. The maximumlikelihood sequence estimator 46 estimates a maximum likelihood sequence based on the weighted values W(Sn), W(Pn) supplied from theweighted value calculators -
FIG. 9 is a trellis diagram to which the maximumlikelihood sequence estimator 46 refers. As shown inFIG. 9 , a signal Sn transmitted by thetransmitter 3 is a signal on which PAM4 mapping has been executed and has four levels of {−1, −1/3, 1/3, 1}. Further, a signal Pn on which partial response equalization has been executed is a signal having seven levels of {−2, −4/3, −2/3, 0, 2/3, 4/3, 2}. - Here, as a result of estimation by the maximum
likelihood sequence estimator 46, in a case where Sn=1, a likelihood is expressed by L(Sn)=k. Further, a likelihood in which a state is Pn=2 is expressed by L(Pn)=m1. A likelihood in which a state is Pn=4/3 is expressed by L(Pn)=m2. A likelihood in which a state is Pn=2/3 is expressed by L(Pn)=m3. A likelihood in which a state is Pn=0 is expressed by L(Pn)=m4. As shown inFIG. 8 , in a case where Pn=2 in a sequence, Sn−1=1, Sn=1. In a case where Pn=4/3 in a sequence, Sn−1=1/3, Sn=1. In a case where Pn=2/3 in a sequence, Sn−1=−1/3, Sn=1. In a case where Pn=0 in a sequence, Sn−1=−1, Sn=1. - In this case, the weighted likelihood LW(Pn) of transition a state of which is Pn=2 is expressed by the
formula 7 with use of the weighted values W(Sn), W(Pn). Similarly, the weighted likelihood LW(Pn) of transition a state of which is Pn=4/3, 2/3 or 0 is expressed by theformula 8 to theformula 10 with use of the weighted values W(Sn), W(Pn). - [Formula 7]
- Weighted likelihood in which a state is Pn=2.
-
LW(P n)=L(S n)*W(S n)+L(P n)*W(P n)=k*W(S n)+m1*W(P n) (7) - [Formula 8]
- Weighted likelihood in which a state is Pn=4/3.
-
LW(P n)=k*W(S n)+m2*W(P n) (8) - [Formula 9]
- Weighted likelihood in which a state is Pn=2/3.
-
LW(P n)=k*W(S n)+m3*W(P n) (9) - [Formula 10]
- Weighted likelihood in which a state is Pn=0
-
LW(P n)=k*W(S n)+m4*W(P n) (10) - The maximum
likelihood sequence estimator 46 calculates a weighted likelihood Lw(Pn) in regard to each transition in the trellis diagram with use of the weighted values W(Sn), W(Pn). Further, the maximumlikelihood sequence estimator 46 estimates the transition that has the largest weighted likelihood LW(Pn) as a maximum likelihood sequence. Themaximum likelihood sequence 46 estimates a maximum likelihood sequence with use of algorithm such as a viterbi algorithm. While a likelihood is expressed by L(Sn)=k in a case where Sn=1 in the above-mentioned example, a weighted likelihood LW(Pn) is calculated, and a maximum likelihood sequence is estimated by the similar method also in a case where Sn=1/3, −1/3, −1. - In this manner, the
communication device 1 of the present embodiment includes aweighted value calculator 45A that calculates a weighted value W(Sn) based on the signal quality of a receipt signal output from the zero-forcingequalizer 4A and aweighted value calculator 45B that calculates a weighted value W(Pn) based on the signal quality of a receipt signal output from thepartial response equalizer 4B. Further, the maximumlikelihood sequence estimator 46 of thecommunication device 1 supplies a weighted value W(Sn) to the state transition based on the output of the zero-forcingequalizer 4A and supplies a weighted value W(Pn) to the state transition based on the output of thepartial response equalizer 4B, thereby estimating a maximum likelihood sequence. Thus, thecommunication device 1 of the present embodiment can weight the signal obtained by zero-forcing equalization and partial response equalization in accordance with property of a transmission line for utilization. Thus, a symbol error rate in thecommunication device 1 can be lowered. -
FIG. 10 is a diagram showing a result of experiment in which receiving property is compared between thecommunication device 1 according to the embodiment and a conventional communication device. InFIG. 10 , the graph G1 represents the relationship between the signal-to-noise ratio of a receipt signal and the symbol error rate in a case where a conventional zero-forcing equalization process is utilized. The graph G2 represents the relationship between the signal-to-noise ratio of a receipt signal and the symbol error rate in a case where a conventional partial response equalization process is utilized. The graph G3 represents the relationship between the signal-to-noise ratio of a receipt signal and the symbol error rate in a case where thecommunication device 1 in the present embodiment is utilized, that is, in a case where the hybrid configuration of the zero-forcing equalization process and the partial response equalization process is utilized. All of the graphs G1 to G3 represent data acquired in the environment of 10G BASE-T. As shown inFIG. 10 , thecommunication device 1 of the present embodiment can realize a similar symbol error rate even in a case where a signal-to-noise ratio is lower than a signal-to-noise ratio acquired in a zero-forcing equalization process by about 2 to 3 db and is lower than a signal-to-noise ratio acquired in a partial response equalization process by about 1 to 2 dB. - In the above-mentioned embodiment, since the property of the class PR1(1+D) is the most similar to the property of insertion loss, the
partial response equalizer 4B executes partial response equalization of the class PR1, by way of example. In another embodiment, apartial response equalizer 4B may be configured to execute partial response equalization corresponding to other classes (PR2 to PR5, etc.) - In the above-mentioned embodiment, the zero-forcing
equalizer 4A is configured to include theDFE 44A, and thepartial response equalizer 4B is configured to include theDFE 44B. In another embodiment, a zero-forcingequalizer 4A may be configured not to include a DFE. Apartial response equalizer 4B may be configured not to include a DFE. - In the above-mentioned embodiment, the
weighted value calculators equalization slicer 43A and a signal-to-noise ratio SNRp of the signal Pn received by the partialresponse equalization slicer 43B. In another embodiment, several expected values may be stored in a table in advance, and an appropriate expected value may be set as a weighted value in accordance with the state of a transmission line. - In the above-mentioned embodiment, the PAM4 mapping is executed on a transmission signal by way of example. The
communication device 1 of the present embodiment can be applied to other modulation systems such as PAM2, PAM3, PAM5, PAM8, PAM16 and NRZ. - “The functionality of the elements disclosed herein may be implemented using circuitry or processing circuitry which includes general purpose processors, special purpose processors, integrated circuits, ASICs (“Application Specific Integrated Circuits”), conventional circuitry and/or combinations thereof which are configured or programmed to perform the disclosed functionality. Processors are considered processing circuitry or circuitry as they include transistors and other circuitry therein. In the disclosure, the circuitry, units, or means are hardware that carry out or are programmed to perform the recited functionality. The hardware may be any hardware disclosed herein or otherwise known which is programmed or configured to carry out the recited functionality. When the hardware is a processor which may be considered a type of circuitry, the circuitry, means, or units are a combination of hardware and software, the software being used to configure the hardware and/or processor.”
- While preferred embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.
Claims (7)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2020-031553 | 2020-02-27 | ||
JP2020031553A JP7368271B2 (en) | 2020-02-27 | 2020-02-27 | Communication device and communication method |
JPJP2020-031553 | 2020-02-27 |
Publications (2)
Publication Number | Publication Date |
---|---|
US20210273830A1 true US20210273830A1 (en) | 2021-09-02 |
US11240074B2 US11240074B2 (en) | 2022-02-01 |
Family
ID=77464085
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US17/184,606 Active US11240074B2 (en) | 2020-02-27 | 2021-02-25 | Communication device and communication method |
Country Status (2)
Country | Link |
---|---|
US (1) | US11240074B2 (en) |
JP (1) | JP7368271B2 (en) |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1997011544A1 (en) * | 1995-09-18 | 1997-03-27 | International Business Machines Corporation | Apparatus and method for noise-predictive maximum-likelihood (npml) detection |
JP4059026B2 (en) | 2002-07-18 | 2008-03-12 | ソニー株式会社 | Adaptive equalization apparatus and playback apparatus |
JP4142537B2 (en) * | 2003-09-19 | 2008-09-03 | 松下電器産業株式会社 | Optical disk device |
JP2006121285A (en) | 2004-10-20 | 2006-05-11 | Sony Corp | Maximum likelihood decoding method and maximum likelihood decoding device |
US7302192B2 (en) * | 2005-04-28 | 2007-11-27 | Menara Networks | Methods of spread-pulse modulation and nonlinear time domain equalization for fiber optic communication channels |
JP4222418B2 (en) * | 2007-01-23 | 2009-02-12 | 日本電気株式会社 | Information reproducing apparatus and information reproducing method |
US8095855B2 (en) * | 2008-03-17 | 2012-01-10 | Agere Systems Inc. | Systems and methods for regenerating data from a defective medium |
JP2011103153A (en) * | 2009-11-10 | 2011-05-26 | Renesas Electronics Corp | Information detecting device and optical disk drive |
JP4910059B2 (en) | 2010-04-21 | 2012-04-04 | 株式会社東芝 | Signal processing apparatus, signal processing method, and signal reproduction apparatus |
US10069653B1 (en) * | 2017-05-12 | 2018-09-04 | Seagate Technology Llc | Blind partial response equalization |
-
2020
- 2020-02-27 JP JP2020031553A patent/JP7368271B2/en active Active
-
2021
- 2021-02-25 US US17/184,606 patent/US11240074B2/en active Active
Also Published As
Publication number | Publication date |
---|---|
US11240074B2 (en) | 2022-02-01 |
JP2021136579A (en) | 2021-09-13 |
JP7368271B2 (en) | 2023-10-24 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP1540820B1 (en) | Method and apparatus for channel equalization | |
Arslan et al. | Channel estimation in narrowband wireless communication systems | |
US7190721B2 (en) | Error convergence measurement circuit for providing convergence of a filter | |
US7006564B2 (en) | Adaptive equalizer | |
US11652673B2 (en) | Decision feedback equalization embedded in slicer | |
KR100278215B1 (en) | Improved detection for digital communication receivers | |
EP1038365B1 (en) | Method and device for improving DFE performance in a Trellis-coded system | |
US6707850B1 (en) | Decision-feedback equalizer with maximum-likelihood sequence estimation and associated methods | |
US8208529B2 (en) | Equalization apparatus and method of compensating distorted signal and data receiving apparatus | |
US4484338A (en) | Data transmission systems | |
JP7200363B2 (en) | Efficient Implementation of Post-Noise Whitening Compensation for Narrowband Filtered Signals | |
US11240074B2 (en) | Communication device and communication method | |
EP1714449B1 (en) | Method and apparatus to perform channel estimation for a communication system | |
Chen et al. | Minimum-SER linear-combiner decision feedback equaliser | |
CN113796016A (en) | Symbol decision device and symbol decision method | |
Parsace et al. | MMSE-DFE equalizer design for OFDM systems with insufficient cyclic prefix | |
US6519282B1 (en) | Method for digital transmission of information | |
Al-Dhahir et al. | Mismatched finite-complexity MMSE decision feedback equalizers | |
US20230308322A1 (en) | Error detection and correction device capable of detecting head position of suspicious error and performing forward error propagation path tracking for providing information needed by follow-up error correction and associated method | |
US20030112903A1 (en) | Combined feedforward filter for a decision feedback equalizer | |
Guenach et al. | Performance analysis of pre-equalized multilevel partial response schemes | |
WO2021037255A1 (en) | Channel compensation method and device | |
Van Welden et al. | Impact of channel estimation errors on the performance of linear FIR equalizers for frequency selective MIMO channels. | |
Raghavan et al. | Imrpoving QPSK Transmission in Band-Limited Channels with Interchannel Interference Through Equalization | |
Agazzi et al. | When can tentative decisions be used to cancel (linear or nonlinear) intersymbol interference?(With application to magnetic recording channels) |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: MEGACHIPS CORPORATION, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:MURATA, SHINICHI;KONDO, TAIJI;YOKOYAMA, YOSHIKI;SIGNING DATES FROM 20210209 TO 20210218;REEL/FRAME:055403/0538 |
|
FEPP | Fee payment procedure |
Free format text: ENTITY STATUS SET TO UNDISCOUNTED (ORIGINAL EVENT CODE: BIG.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: DOCKETED NEW CASE - READY FOR EXAMINATION |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: EX PARTE QUAYLE ACTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: RESPONSE TO EX PARTE QUAYLE ACTION ENTERED AND FORWARDED TO EXAMINER |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NOTICE OF ALLOWANCE MAILED -- APPLICATION RECEIVED IN OFFICE OF PUBLICATIONS |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: PUBLICATIONS -- ISSUE FEE PAYMENT RECEIVED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: PUBLICATIONS -- ISSUE FEE PAYMENT VERIFIED |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |